In cutting CFRP, the major problem is severe tool wear and inferior surface quality. Theoretically the tool wear is hardly influenced by the cutting speed under practical cutting condition. The experimental result nearly agrees with the theory as the main characteristic. However, the tool wear shows weak peak at relatively low cutting speed as the minor characteristic. The purpose of this study is to clarify the mechanism of this peak phenomenon. Relationships between the cutting speed and the tool wear are investigated in an edge cutting test of CFRP pipe produced by the FW method at a constant cutting speed with the straigh cutting edge tool. The flank wear width (VB max) takes the peak at the cutting speed of 40 m/min and that VBmax decreases gradually with increase of the cutting speed over 40 m/min. In cutting CFRP, the tool wear is mechanical wear which consists of the abrasive wear of hard grain and the ploughing of it. The carbon fiber and its broken pieces rub against the tool flank. There occur cracks and separations under the cut surface. They make many cavities on the cut surface and the contact pressure between the tool flank and the cut surface (carbon fibers) decrease. Then they decrease the tool wear. The effect of cracks on the tool wear is the least and the rubbing is most intense at the cutting speed of 40 m/min. Therefore, the tool wear becomes the largest at this cutting speed.